1. Virtual Unenhanced Images at Dual-energy CT: Influence on Renal Lesion Characterization
Virtual noncontrast images yield high diagnostic performance (AUC 0.91; average error rate, 12%) for helping to differentiate contrast agent–enhanced from unenhanced renal lesions.
Diagnostic performance is higher for unenhanced compared with virtual unenhanced images for differentiating contrast-enhanced from unenhanced renal lesions (AUC 0.91 vs 0.96, respectively; P < .001).
Whereas a higher error rate may be acceptable in the setting of incidentally discovered renal lesions, this decrease may not be acceptable for dedicated imaging of indeterminate renal lesions.
In a 61-year-old with hematuria, contrast-enhanced CT shows a hypodense renal lesion (red arrow) is  hypodense on the virtual noncontrast image (green arrow) and isodense unenhanced image (blue arrow), mimicking false-positive enhancement.  
Meyer M et al. Published Online: Mar 12, 2019